502 Refurbishment

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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:02 pm

Frank, they are only hollow for about 3/16" or so and the rest of the rivet is solid.

Also, I have updated my previous post with better detailed information. If you cannot get them easily, I have them for sale too.
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:23 pm

Back to the comment about track lengths. It's important to understand if your tracks are matched or not and if not, how much different are they. You will understand shortly.

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Putting tracks on is quite simple when your Diablo is upside down. Fold the ends of the track toward the center and set it on the Diablo bogies. Then flip the end out toward the idler sprocket and route the track around the idler, across the chassis and up around the drive sprocket. Pull the tracks together. I use a C Vise Grip. A ratchet strap pulling on the cleats works just as well.

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Once pulled together, you install the lacer pin and fold the ends over. Do not reuse pins as they could break at the bend and that would ruin your Diablo ride.

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Now - here is the most important thing you need to know about adjusting the tracks. When you are done tightening, the jacking bolts for adjusting the tracks must be sticking out the same distance on each side. Having them equal places the output shaft of the gearbox parallel with the chassis side to side and thus does not try and twist the gearbox in the post mount. If your jacking bolts are off just a little, the drive shaft is torqued sideways in the gearbox and the only place it can move is to shove the seal over as the lower bearing is not moving. Drive it around for a while this way and you will take out the seal and the bearing.

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I apologize for the poor picture, but I hope you get the idea. So back to track lengths, if your tracks are different, one will be loose and the other will be tight. And the more different they are, the greater difference in tension. But better to have one loose track and one tight than to take out the gearbox. Driving the Diablo around for a bit getting the tracks in the snow and moisture sometimes stretches out the track that is tight and you can re-adjust as they change.

Regarding tension, my preference is to have them moderately tight at the most. Tracks that are too tight damage sprockets. If you have them too loose, they might slap on the bottom of the chassis and that means you need to tighten them some.

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Plan on several hours to work on the tracks.
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:27 pm

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On to the top side refurbishment. Simple things like installing the gas tank for starters.

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Don't tighten the gas tank strap just yet.

Fill the gearbox with 4 to 6 ounces only of oil. If you fill to the side hole in the gearbox, it is sure to leak.

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Install the snow shield around the gearbox to keep the snow out of the engine compartment, install motor mounts and things like this.

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Too many Diablos and parts to count.
Yamaha Apex (it outruns the Diablo for sure)
Yamaha 600 SX
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:32 pm

Install the handlebars with the dash on them. This puts the gas tank where it needs to be. Now you can tighten the strap, but only snug the strap up. The gas tank is not going anywhere, so no need to crank the strap down. If you do, all you do is damage the solder seal of the side of the tank! :o

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Loosen up the half moon handles. This one came with a couple of bolts holding them on which must have been hard on the gloves. I use shovel rivets and push on caps which are very close to the original pins.

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If the dash bushing for the recoil is worn out, install a new one.

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Route new throttle and brake cables if needed. I get the end of cable right at the opening. Then reach in with a pic and pull it toward the hole enough to grab it.

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Maybe an hour to put the handle bars on, bolt down the tank, fix up the handles and pull some new cables.
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:41 pm

The Secondary Clutch should come apart. If you have two people, you might be able to work together to compress the spring and remove the snap ring. I prefer to put the clutch in a press to get the snap ring off and then back on again.

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Once the spring tension is off, the clutch slides right apart. I clean the oil and grease off the clutch and sandblast the rust off the surfaces. An original clutch would have 3 pins that are riveted in place. If they are loose, you can tighten them by hammering down the peen of the rivet some.

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If you have cracks in the faces of your clutch, it may not be repairable. Small cracks are ok, but small cracks become big cracks over time. If you pins are bad, people use shoulder bolts in new holes and then cut the heads off to recreate the pins. A good topic for a future tutorial.

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Install the clutch before you install the hood mount or you won't get the clutch past the mount.

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About an hour to work on and install the Secondary Clutch.
Too many Diablos and parts to count.
Yamaha Apex (it outruns the Diablo for sure)
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:49 pm

This is a good time to freshen up the exhaust pipe if needed.

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Also a good time to reinstall the brake. Start by installing the brake disc. If your splines are loose, that is a result of spline wear on the disc. The disc is made softer than the shaft so the disc is the sacrificial lamb. You can drive it till the splines give out then replace it without hurting the shaft. Clean up the hollow spacers for the mounting bolts. These spacers should slide freely when the brake is mounted to create a floating brake rotor. Put some grease on these spacers.

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The brake is fairly simple. Clean the parts up and assemble. When you install the cable, set it such that the lever is just to the left of 12 o'clock. Putting it here gives you the best brake with the least travel of the cable because the arm is already past center. Once set, from here on out if you need more brake, you just tighten the castle nut a bit.

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Brake and exhaust - about an hour.
Too many Diablos and parts to count.
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Sun Jan 17, 2016 9:57 pm

Time to install the hood. Set the hood with the hood mount on the chassis and bolt it in place. It does not really have much adjustment in how it sits on the chassis, but you can move it some or elongate some holes to get the hood pin to line up with the hole.

Now is a good time to check the headlights.

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Clean them up and make sure when you have the lamp in place and using an ohm meter, you get continuity between the wire lead and the headlight frame. This means the lamp is installed correctly and should light when you have it together. Install the lights against the nose cone and route the screws through the nose cone and through the hood bracket. Be careful not to drop a lens or over-tighten the screws. Headlight lenses are expensive :oops:

This Diablo needed a new nose cone as the original was pretty beat up. I paint the perimeter of the piece to match what it should look like.

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Then install it on the hood.

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Hood, headlights and nose cone - about an hour or two. On to the motor tomorrow!
Too many Diablos and parts to count.
Yamaha Apex (it outruns the Diablo for sure)
Yamaha 600 SX
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Mon Jan 18, 2016 10:28 pm

Please, please, please use a clutch puller and a flywheel puller to remove these components. I would much rather borrow you or sell you a puller than to sell you a flywheel or a clutch. I can make pullers all day long, but we are not making clutches and flywheels anymore.

And please, I'm not trying to insult anybody with this next comment.

I talk to at least a dozen people a year who tell me "Hey Bruce, I just got this Diablo. It's been sitting for 30 years and we got it started yesterday. Just pouring a little gas down the carb or rebuilding the carb and away we went. Wow are we having fun".

When I pull a Diablo in the shop, I may check to see if the engine is free, but I NEVER try and start it. Why you ask? This is what motors look like on the inside after sitting many years.

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For whatever reason, most times the piston is rusty and so is the cylinder. The engine seals are sure to leak and who knows what else is wrong with it. So someone is out there driving all that rust into their lower crankcase and running an engine lean because the crankcase leaks. Believe me, that is a far more expensive motor rebuild down the road compared to if you had just taken it apart and did a little housekeeping. If someone feels otherwise or has an opinion they would share, I'd love to hear it.

So every motor gets stripped down to the crankcase. Flywheel off, ignition plate out (stamp a location mark so you put it back where it was), bearing covers off and piston removed. I clean it up, get some cleaner up into the crankcase and flush it out good. Typically, the crank bearings and rod bearing are ok at this point. If they are not, then you have a more extensive rebuild. But for most, now it's a matter of putting it back together.

I can't explain why, but about 1 motor in 10, I come across a flywheel side of the crankshaft that is rusty. So rusty that a seal would never seal against it.

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Luckily, SKF makes a Speedi Sleeve that repairs the problem. These are very thin sleeves that are very specific in size meant to press easily over the damaged area.

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Just a few light taps with a pipe just big enough to fit over the shaft end and it presses right on and just like that, you have a brand new bearing surface.

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After any repairs needed, start by lubricating the crank bearings and rod bearing with assembly lubricant. Tap the crank seals in to the bearing retainers. Put them in dry, don't try and put permatex or something on the outer surface or they won't seat properly and probably will slide right out as they are not in the retainer with much force. When you pulled the seals out, you may have found one in backwards. This was a Hirth error and when reinstalling them, they should be installed with the springs inward. By now, you have the bearing retainer gaskets off. I clean those up with a little brakecleen and get them dry. Then smear an ever so light skim of permatex on them. These gaskets only go on one way, so get it right.
Too many Diablos and parts to count.
Yamaha Apex (it outruns the Diablo for sure)
Yamaha 600 SX
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Re: 502 Refurbishment

Postby Schoobytwo (Bruce) » Mon Jan 18, 2016 10:29 pm

Clean up the piston and free up the rings if necessary. Another quirky thing with some of these original Hirth motors is you will find the piston in backwards. By backwards, I mean the ring stop pins are on the exhaust side of the piston and if you clean the piston off real good, you might also see the arrow pointing toward the exhaust which is always an indication that is the exhaust side. The two contradict each other. All my experience says the pins should always be toward the intake side of these motors because the ring ends are far less likely to pop out in the intake port than they are in the exhaust port. If you find one that way, I suggest to put it back in that way as it would be hard for the rings to re-seat.

Hone the rust out of the cylinder. Put a good cross hatch in it if you can. Assemble the motor with new gaskets. Torque the cylinder head bolts to 220 inch pounds. Install the spark plug. Before I go any further, I install plates over the intake and exhaust ports and pump a few pounds of air in to the pulse port of the engine and see if the crankcase holds the pressure. If it holds, you know you have a well sealed motor and it should not run lean and burn a piston.

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Install a new plug wire. It's easily done while the ignition plate is out. Install new points too. Install the ignition plate and install the flywheel. Then adjust your points to 0.016" through the windows in the flywheel. Finish installing covers and brackets and you are ready to install back in the Diablo.

About 3 to 4 hours.
Too many Diablos and parts to count.
Yamaha Apex (it outruns the Diablo for sure)
Yamaha 600 SX
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Re: 502 Refurbishment

Postby jayvee43 » Tue Jan 19, 2016 6:12 pm

I like those speedi-sleeves Bruce. I do have to remember to get some from you on my next order,. I guess i forgot this time around. Ofcourse, your crank on this one is a lot more riddled with rust than mine was, specially where the seal lips ride on the crank.

Nice job. I'm making all kinds of notes for when I tackle my 502 next year. ;)

Keep it coming I'm learning a lot.

Jesse
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1967 Diablo rouge 500
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